Stable methylchloroform compositions



3,099,694 STABLE METHYLCHLOROFORM COMPOSITIONS George N. Grammar and Percy W. Trotter, Baton Rouge, La, assignors to Ethyl Corporation, New York, N.Y., a corporation of Virginia No Drawing. Filed May 27, 1960, Ser. No. 32,105 10 Claims. (Cl. 260-6525) This invention relates to the degreasing of metals. In particular, it relates to stable solvent compositions composed of 1,1,l-trichloroethane containing mixtures of stabilizing additives which prevent metal induced decomposition.

The problem of stabilizing chlorinated aliphatic hydrocarbons-viz, carbon tetrachloride, trichloroethylene, tetrachloroethylene, ethylene dichloride, etc., useful as solvents for degreasing metals has received considerable attention by skillfiul chemists over many years. It has, however, become increasingly apparent that the discoveries relative to the stabilization of particular chlorinated hydrocarbon solvents are neither applicable nor translatable to the problems of stabilizing ether chlorinated hydrocarbon solvents. Even where a successful stabilizing additive has been found for a particular chlorinated hydrocarbon solvent, the stabilized composition still may not meet the rigorous requirements of commercial applications.

Some stabilizing additives thus provide some degree of protection against decomposition of the chlorinated hydrocarbon solvents or against attack upon the metals themselves in liquid and vapor phase but yet do not provide sufiicient protection for commercial use. A commercially acceptable stabilizing additive, for example, must also be capable of inhibiting against metal induced decomposition of the chlorinated hydrocarbon solvent under hydrolytic conditions. Often a stabilizer, otherwise acceptable commercially, fails to meet this stringent requirement and when a very small amount of water is introduced into the system severe corrosion of the metal and decomposition of the solvent results. Also, a stabilizing additive otherwise acceptable, is often rejected by the trade because it adds color to the chlorinated hydrocarbon solvent. Cost of the stabilizing additive is another factor which can influence the commercial acceptance of stabilizers.

Insofar as stabilizing 1,1,1-trichloroethane (methylchlo roform) is concerned, the problems are even more acute. From the standpoint of metal induced decomposition, 1,1,1-trichloroethane departs drastically from the norm of other chlorinated hydrocarbons. For example, metals, especially aluminum, will last for days or weeks without being attacked by ordinary chlorinated hydrocarbon solvents, but in the presence of 1,1,l-trichloroethane, however, aluminum is vigorously attacked and the 1,1,l-triohloroethane solvent reduced to a blackened or charred mass within minutes. Only a few stabilizers are known which are reasonably effective in inhibiting l,l,1-trichloroethane against such attack and why these few stabilizers are effective is not known. The mere fact however that a stabilizer will inhibit decomposition of other chlorinated hydrocarbons means absolutely nothing in relation to stabilizing 1, 1,1-trichloroethane.

The problem of stabilizing 1,1,1- trichloroethane in the vapor phase is especially acute because even a stabilizer which is useful for stabilization of the liquid phase is useless for stabilizing the vapor phase unless it has sufficient volatility to stabilize the vapor phase, and yet it cannot have such volatility as to unduly deplete the liquid phase. No commercial vapor phase stabilizer for 1,1,1- trichloroethane is known.

It is accordingly an object of this invention to provide stabilized compositions which are highly efiective for deite States Patent greasing aluminum, iron and other metals. A particular object is to provide 1,1,1-trichloroethane solvent compositions which retain chemical passivity during repeated cycles of exposure to metals at processing conditions, and against the degradation influences of moisture, elevated temperature, contact with metals and metal halides, and light. Another object of the present invention is to provide compositions especially suitable for the vapor phase degreasing of aluminum and other metals. A further object is to provide additive compositions especially adapted for use in methyl chloroform as stabilizers therefor.

'Izhese and other objects are achieved according to the present invention which comprises forming a stable 1,1,1-trichloroethane solvent composition by dissolving within 1,1,l-tricl1loroethane a novel mixture of additives in a quantity sufficient to inhibit the -1,1,1-trichloroethane against decomposition. The stabilizing mixture is one consisting essentially of a dioxolane, a mono-olefin and an epoxide compound. On the basis of outstanding efiectiveness and low cost the preferable class of stabilizing additives are those wherein the dioxolane compound is a 1,3-dioxolane compound containing up to 2 alkyl substituents each having from 1 to 2 carbon atoms, the monoolefin is an alkene hydrocarbon having from about 6 to about -8 carbon atoms, and the epoxide is a compound containing from about 3 to about 4 carbon atoms and up to l chlorine atom.

In an especially preferred embodiment of this invention the stabilizing mixtures of dioxolane, mono-olefin and epoxide compounds added to the 1,1,1-trichloroethane are preferably 1,3-dioxol ane compounds, containing up to 1 alkyl substituent having from 1 to 2 carbon atoms, a mono-olefin which is an alkene hydrocarbon having from about 6 to about -8 carbon atoms, and a monochloroepoxide containing from about 3 to about 4 carbon atoms. These systems have superb stabilizing properties particularly against iron under severe hydrolytic conditions, and even in the stabilization of l, l,l,-trichloroethane in the vapor phase.

An even more highly preferred embodiment is one wherein the stabilizing mixture for 1,1,1-triehloroethane consists essentially of l,3-dioxolane, diisobutylene and epichlorohydrin. The particular combination of additives shows outstanding stabilizing properties, and in the presence of iron does not discolor or cause corrosion of the iron even under severe hydrolytic conditions. In short, on a cost-effectiveness basis this trinary system is particularly outstanding.

In yet another especially preferred embodiment of this invention, the dioxolane, mono-olefin and the epoxide compounds are blended together to form additive concentrates or corrosion inhibitor compositions. These compositions form homogenous and essentially colorless solutions which can be rapidly and conveniently added to .1,l,l-trichloroethane in all desired proportions. The inhibited 1,1,1-trichloroethane compositions thus formed are highly resistant both to decomposition of the solvent and to corrosion of the metal with which the solvents are placed in contact. In particular, these additive concentrates when blended with 1,1,1-trichloroethane form highly useful compositions for degreasing the surfaces of metals. Accordingly another preferred embodiment of this invention is that of degreasing metal by contacting the surfaces of metal with 1,1,1-trichloroethane while maintaining a mixture of a dioxolane, a mono-olefin and an epoxide dissolved within the 1,1,1-trichloroethane in suflicient quantity to inhibit the l,1,l-trichloroethane against decomposition.

In accordance with the practice of this invention, 1,1,1- trichloroethane is provided with an additive concentrate composed of a mixture of from about 10 percent to about 6 0 percent of a di-oxolane compound, from about 30 to about 80 percent of a mono-olefin compound and from about 10 to about 60 percent of an epoxide compound. A particularly preferred inhibitor composition is one composed of about 20 to about 40 weight percent of a This invention then is based in part on the discovery that the value and effectiveness of these dioxolanes as stabilizers for 1,1,1-trichloroethane can be even further enhanced by the addition thereto of specified mono-olefin dioxolane compound, from about 40 to about 60 weight 5 and epoxide compounds. In particular, the present stapercent of an alkyl mono-olefin compound and from about bilizing mixtures considerably enhance the ability of the to about 30 weight percent of an epoxide compound. 1,1,l-trichloroethane to resist deterioration in the presence This particular composition is particularly preferred be of iron metal and its alloys. This is true even under secause it provides especially high stabilizing benefits under vere hydrolytic conditions.

general commercial degreasing conditions and is also 10 Thus, additive concentrates or inhibitor compositions available at low cost. made up of mixtures of dioxolanes, and specified mono- Thus, according to this invention a small amount of this olefin and epoxide compounds can be preformed and stabilizing mixture, in quantity suflicient to inhibit the added to 1,1,1-trichloroethane and outstanding results 1,1,1-tn'chloroethane against decomposition, is added to achieved. As stated, this is especially true where the 1,1,l-trichloroethane. Generally a minor amount of this stabilized 1,1,l-trichloroethane-dioxolane compositions stabilizing mixture, suitably about 0.3 to about 15 Weight are used in contact with iron and under hydrolytic condipercent (based on the weight of the total inhibited soltions. However, the several additive ingredients of the vent), added to the 1,1,l-trichloeth-ane slovent forms a stabilizers of this invention can be blended with the highly effective system which resists deteriorating influ- 1,1,1-trichloroethane either individually or in various subences suchas contact with aluminum-even freshly excombinations. posed aluminum surfaces-copper, zinc and other metals, The following representative experimental data proexposure to light and subjection to elevated temperatures. vide a sound basis for a clear appreciation of this inven- These mixtures are particularly effective in preventing at tion. 'In the example immediately following, a stabilized tack upon iron metal, or alloys of iron, which are especomposition of 1,3dioxolane-1,1,1-t1ichloroethane was cially susceptible to attack under hydrolytic conditions. employed with iron under degreasing conditions. Ac- The stabilizing mixtures also form essentially colorless cordingly, to 100 parts by weight of methyl chloroform or water white solutions which are accepted without contained within a reaction vessel was added 3 parts by prejudice by the trade. This attitude is in sharp conweight of 1,3-dioxolane. Above the reaction vessel was trast to many other situations where stabilizing mixtures then suspended two tared strips of soft iron. The mixare rejected on the basis that they add color to the solture was then continuously refluxed for 67 hours, the vent. A preferred concentration of any of these .stavapors condensing upon the strips of iron and pouring bilizing mixtures in 1,1,1-trich1oroethane is from about 4 back into the vessel. After this time the tared metal strips to about 10 weight percent because of the excellent propwere dried, cleaned and reweighed. The average weight erties of the resulting composition to resist deterioration. loss of the two iron strips was 0.14 pecent by weight. A 6 percent concentration is especially preferred because To show the benefits derived from the practice of this of the excellent properties of the resulting composition invention wherein a mono-olefin and an epoxide comto resist deterioration under commercial operating conpound are used in combination with dioxolane, a mixditions. ilt will be understood however that the concenture of dioxolane and the former compounds was added trations of the present stabilizers can be varied beyond to 1,1,1-trichloroethane, and a demonstration per-formed the ranges given above without loss of most of the beneunder similar conditions, as in the following example: fits of this invention and without departing from the scope EXAMPLE I of this invention.

It was heretofore discovered by one of the present q Parts by welght of methyi .clilomfqmcomanied inventors that the dioxolane compounds when used alone Y a reactor was {added a siablhzmg mlxture i are highly effective stabilizers for 1,1,1-tn'chloroethane. l? Parts by by It has now been discovered that the inhibiting powers of dusobutylene Parts by welght of eplchlowhydnn' these dioxolane compounds can be even further enhanced N9 3 tared smp mm y Suspended above by the use of particular mono-olefin and epoxide combl'hzed Solvent colitamed wl'thm the .reactor' W tempounds. This is indeed unexpected for the latter comm the mixture was then Tamed t0 bolhng pounds in themselves, alone or admixed, are poor'staibilizreflux contmued for 67 hours After that w the ers for 1,1,1-trichloroethane. Thus, while the discovery i was removed from the reactor and exjammed' The of these dioxolane compounds as inhibitors for 1,1,1,- appeaired completely unaffected P Its Surface trichloroethane has been of great importance and signifimamed bright and clear- The 1h101 0eth ane solcance, dioxolane-lgl,l-trichloroethane systems neverthevent i colorless or water The welght 1055 less do have one shortcoming. The dioxolane-l,1,1- of the Smp was less thanoos percent trichloroethane compositions do leave something to be EXAMPLE II desired when hydrolytic conditions occur and these com- The foregoing example was repeated in all details expositions are in contact with iron, particularly w th cercept that a tared strip of aluminum metal was substituted tam. forms of iron and under extended hydrolytic condifor the iron. After refluxing for 68 hours there was no non-s The iron, under hydrolytic condntons, does underevidence of any weight loss of aluminum, and the solvent go significant corrosion. The corrosion of H011 under remained water white. hydrolytrc conditions is considerably and significantly The following Table I shows other three-component reduced by use pursuant to this invention of a dioxolane, systems of highly preferred additive concentrates conan alkyl mono-olefin and an epoxide compound in the sisting of dioxolane, mono-olefin and epoxide compounds. 1, 1,1-trich1oroethane solvent In particular, the value of These'systems of additive concentrates correspond in reldioxolane as; a. vapor phase inhibitor is greatly enhanced ative concentrations of components to each other as that by'the addition thereto of a monoolefin and an epoxide. 0f the stabilizing mixture employed in Example I.

Table 1 Ex. Dloxolane eom- Mono-olefin compound Epoxide compound pound 1-chl0ro-3,4-epoxy butane. 1-chloro-2,3-epoxy butane. 2-chl0r0-3,4epoxy butane. l-chloro-2,3-epoxy butane.

EXAMPLES HLVI The systems of additive concentates, III-VI, respectively, are added to 1,1,l-trichloroethane solvent in sufiicient quantity to form .03, 0.5, 1, 2, 4, 5, 6, 10, 12 and percent compositions respectively. The procedure of Example I is again repeated with each of these compositions. At the termination of each of the runs the 1,1,1- trichloroethane solvent remains essentially colorless and there is no visible evidence of any corrosion.

In the tollowing Examples (VII-XVII), a wide variety of :additive concentrates, varying with respect to the individual compounds employed and with respect to their relative proportions to each other, are formed as shown in Table II.

Table II Dioxalane compound Mono-olefin compound Epoxide compound XIII- 30 percent 5-ethyl-1,3-dioxo1ane-- 60 percent 2,3,3-trimethyl pentene-l.-- XIV 50 percent 1,3-dioxolane 40 percent heptene-l XV... 60 percent 1,3-diox0lane 30 percent 2,3,4-trimethyl pentene-2 XVI percent 1,3-diox0lane 70 percent 2,3,4-trimethyl pentene-2 XVII 10 percent 1,3-dioxo1ane 80 percent 2,3-dimethyl butenc-2 percent l-hexene 40 percent 2,3'dimethy1 butene-l. 40 percent 2,3-dimethyl butene-2 50 percent Z-methyl pentene-Z-.- 50 percent 3-methyl pentene-2 50 percent 2,4,4-trimethyl pentcn 60 percent 2'chlor0-3, A-epoxy butane. 50 percent l-chloro-2,3-epoxy butane. 40 percent lchloro-2,3-epoxy butane. 30 percent 1 chloro-3Aepoxy butane. 20 percent 1-chloro-3,4-epoxy butane. l0 ptgcent 2-chlor0-3,4-epoxy butane.

o. 10 pggcent 1-ehloro-3,4-epoxy butane.

Do. 10 percent 1-chl0ro-2,3-cpoxy butane.

The stabilizing mixtures, or corrosion inhibitor compositions, shown in Examples VII through XVII are added to 1,1,1-trichloroethane to form stabilized 1,1,l-trichloroethane compositions. The corrosion inhibitor compositions are added to the 1,1,1-trichloroethane in suflicient quantity to form 0.3, 0.5, 1, 2, 4, 5, 6, 10, 12 and 15 weight percent compositions of the stabilizing mixtures in 1,1,1-trichloroethane.

Example I is then repeated with each of these stabilized 1,1,1-trichloroethane compositions. As in Example I, the solvents show little or no signs of decomposition. The metals also show little or no signs of chemical attack.

When Example 11 is repeated with the stabilized 1,1,1- trichloroethane solvents formed as in Examples VII through XVII, similar results are obtained.

The corrosion inhibitor compositions of Examples XVIII through XXVI (Table III) are added to 1,1,1- trichloroethane in sufficient quantity to form 0.3, 0.5, 1, 2, 4, 5, 6, 10, 12 and 15 weight percent compositions of the stabilizing mixtures in 1,1,1-trichloroethane. Examples I and II are then again repeated with each of these compositions. As in Examples I and II, the solvent compositions show little or no signs of decomposition and the metals are essentially unattacked.

boiling within a range of from about 50 C. to about 120 0., preferably from about to about 85 C., and the like. Other preferred dioxolane compounds include 2,2-dimethyl-1,3-dioxolane, 4,4-dimethyl-1,3 dioxolane, 5,5-dimethyl-1,3-dioxolane, 2,4-dimethyl-1,3-dioxolane, 2,5-dimethyl-1,3-dioxoiane, 4,5-dimethyl-1,3-dioxol ane, 2,2-diethyl-1,3-d-ioxolan-e, 4,4-diethyl-1,3-dioxolane, 5,5-diethyl-1,3-dioxolane, 2,4-diethyl-1,3-dioxolane, 2,5-diethyl-1,3-dioxolane, 4,5-diethyl-1,3-dioxolane, 2-methyl-2- ethyl-1,3-dioxolane, 2-methyl-4-ethyl 1,3 dioxolane, 2- rnethyl-S-ethyl-l,3-diox-olane, 2-ethyl-4-methyll,3 dioxolane, Z-ethyI-S-methyl-l,3-dioxolane, and the like.

Nonlimiting examples of mono-olefins of this invention include hexene-l, hexene-Z, hexene-3, 2,3-dimethyl butene- 1, 2,4-dimethy1 butene-l, 3,4-dimethyl butene-l, 2,3-dimethyl butene-2, 3-ethyl butene-l, 2-methyl pentene-l, 2- rnethyl pentene-2, 3-methyl pentene-Z, heptene-l, 3-methyl hexene-l, 3,3-dimethyl pentene-Z, 3-methyl-3-ethyl butene- 1, 3,3-diethyl propene-l, octenel, octene-3, Z-methyl heptene-l, 2,3-dimethyl hexene-l, 2,4-dimethyl hexene-l, 3-ethyl hexene-Z, 2-methyl-3-ethyl pentene-l, 2-methyl-4- ethyl pentene-l, 3,3-diethy1 butene-l, 1,1,2-trimethyl butene-Z, and in general those compounds boiling within a range from about 50 C. to about 120 C., preferably from about 65 to about 85 C., and the like.

Table III Dioxolane compound Mono-olefin compound Epoxide compound 10 percent 2,2-diethyl-L3-dioxolane 80 percent Z-methyl pentenc-2 10 percent epihydrin.

20 percent 1,3-epoxy propane. 30 percent 3,4-epoxy butane. 40 percent epihydrin.

40 percent-3,4-epoxy butane. 50 percent-1,3-epoxy butane.

10 percent-epihydrin.

60 percent-1,3-epoxy butane. 20 percent-epihydrin.

In the practice of this invention, a minor concentration of the mixture of components or additive concentrates is added to the 1,1,1-trichloroethane. Any concentration of these compounds will produce some stabilizing effect, and the quantity of the stabilizing mixture to be added is therefore largely contingent upon the use for which the stabilized solvent will be employed. Generally, however, stable compositions consisting essentially of from about 0.3 to about 15 weight percent of the mixture of additives in 1,1,1-trichloroethane are 'formed. These compositions Nonlimiting examples of epoxides are such epoxides as epichlorohydrin, 2-chloro-3,4-epoxy butane, 1-chloro-2,3- epoxy butane, 1-chloro-2,4-epoxy butane, l-chloro-3,4- epoxy butane, 2-chloro-3,4-epoxy butane, 1-chloro-2,4- epoxy butane, and in general those compounds boiling within a range from about 50 C. to about 120 C., preferably fromabout 65 to about C., and the like. Other highly suitable epoxides include epihydrin, 1,3-epoxy propane, 3,4-epoxy butane, 1,3-epoxy butane, 1,4-epoxy butane, 2,3-epoxy butane, and the like.

Having described the invention, what is claimed is:

We claim:

1. A stable solvent composition for the degreasing of metals, said solvent being composed of 1,1,1-triehloroethane within which is dissolved from about 0.3 to about 15 weight percent of a mixture of stabilizing additives consisting essentially of a dioxolane, a mono-olefin, and an epoxide, sufi'icient to inhibit the 1,1,1-trichloroethane against decomposition, said dioxolane being a 1,3-dioX- 01121116 compound containing up to 2 alkyl substituents each having from 1 to 2 carbon atoms, said mono-olefin being an alkene hydrocarbon having from about 6 to about 8 carbon atoms, and said epoxide being a compound containing from about 3 to about 4 carbon atoms and up to l chlorine atom.

2. The composition of claim 1 wherein the dioxolane is 1,3-dioxolane.

3. The composition of claim 1 wherein the mono-olefin is diiso-butylene.

4. The composition of claim 1 wherein the epoxide is epichlorohydrin.

5. The composition of claim 1 wherein the stabilizing mixture of additives is present'within the 1,1,1-tfichlroethane at a concentration of from about 4 to about 10 weight percent.

6. The composition of claim 1 wherein the stabilizing mixture of additives is present within the 1,1,1-trichloroethane at a concentration of about 6 weight percent.

7. The composition of claim 1 wherein the dioxolane is 1,3-diox0lane, the mono-olefin is diisobutylene and the epoxide is epichlorohydrin.

8. The composition of claim 7 wherein the stabilizing mixture of additives is present within the 1,1,1-trichloroethane at a concentration of from about 4 to about 10 weight percent.

9. The composition of claim 7 wherein the stabilizing mixture of additives is present within the 1,1,1-trichloroethane at a concentration of about 6 weight percent.

10. A 1,1,1-trichloroeth'ane corrosion inhibitor composition composed of a mixture of from about 10 percent to about 60 percent of a dioxolane, from about percent to about 80 percent of a mono-olefin and from about 10 percent to about percent of an epox-ide, based on the weight of the corrosion inhibitor composition, said dioxolane being a 1,3-dioxolane compound containing up to 2 alkyl substituents each having from 1 to 2 carbon atoms, said mono-olefin being an a-lkene hydrocarbon having from about 6 to about 8 carbon atoms, and said epoxide being a compound containing from about 3 to about 4 carbon atoms and up to l chlorine atom.

References Cited in the file of this patent UNITED STATES PATENTS 1,904,450 Harris Apr. 18, 1933 2,364,588 Morris etal Dec. 5, 1944 2,371,645 Aitchiso'n et a1 Mar. 20, 1945 2,517,894 Larcher 1 Aug. 8, 1950 3,008,999 Kauder Nov. 14. 1961 

1. A STABLE SOLVENT COMPOSITION FOR THE DEGREASING OF METALS SAID SOLVENT BEING COMPOSED OF 1,1,1-TRICHLOROETHANE WITHIN WHICH IS DISSOLVED FROM ABOUT 0.3 TO ABOUT 15 WEIGHT PERCENT OF A MIXTURE OF STABLIZING ADDITIVES CONSISTING ESSENTIALLY OF A DIOXOLANE, A MONO-OLEFIN, AND A EPOXIDE, SUFFICIENT TO INHIBIT THE 1,1,1-TRICHLOROETHANE AGAINST DECOMPOSITION, SAID DIOXOLANE BEING A 1,3-DIOXOLANE COMPOUND CONTAINING UP TO 2 ALKYL SUBSTITUENTS EACH HAVING FROM 1 TO 2 CARBON ATOMS, SAID MONO-OLEFIN BEING AN ALKENE HYDROCARBON HAVING FROM ABOUT 6 TO ABOUT 8 CARBON ATOMS, AND SAID EPOXIDE BEING A COMPOUND CONTAINING FROM ABOUT 3 TO ABOUT 4 CARBON ATOMS AND UP TO 1 CHLORINE ATOM. 